1 files changed, 41 insertions, 0 deletions
diff --git a/src/engine/physics.hpp b/src/engine/physics.hpp
new file mode 100644
index 0000000..6a8abda
--- /dev/null
+++ b/src/engine/physics.hpp
@@ -0,0 +1,41 @@
+#pragma once
+
+#include <box2d/box2d.h>
+#include <vector>
+
+// Box2D rigid-body world. The building structure runs on the custom Verlet
+// solver (see build_graph / verlet); this exists as the foundation for M4
+// projectiles and any terrain collision they need.
+struct PhysicsBody {
+    b2BodyId  id;
+    b2Vec2    size;      // half-width, half-height for box shapes
+    float     red, green, blue, alpha;
+    bool      is_static;
+};
+
+class PhysicsWorld {
+public:
+    PhysicsWorld();
+    ~PhysicsWorld();
+
+    PhysicsWorld(const PhysicsWorld&) = delete;
+    PhysicsWorld& operator=(const PhysicsWorld&) = delete;
+
+    void step(float dt);
+
+    // Create a static box (terrain, walls).
+    PhysicsBody* add_static_box(b2Vec2 center, float half_w, float half_h,
+                                float r = 0.3f, float g = 0.3f, float b = 0.3f);
+
+    // Create a dynamic box (projectiles, debris).
+    PhysicsBody* add_dynamic_box(b2Vec2 center, float half_w, float half_h,
+                                 float r = 0.8f, float g = 0.6f, float b = 0.2f);
+
+    const std::vector<PhysicsBody>& bodies() const { return bodies_; }
+
+    b2WorldId world_id() const { return world_id_; }
+
+private:
+    b2WorldId               world_id_;
+    std::vector<PhysicsBody> bodies_;
+};